The presence of
estramustine-binding protein has been suggested to positively correlate with the effect of the cytotoxic
drug estramustine, a combination of
estradiol and
nornitrogen mustard used in the treatment of prostatic
carcinoma. This study demonstrates expression of
estramustine-binding protein in a series of
meningioma using different
ligand-based and immunological techniques. Scatchard plot analysis showed specific binding sites for [3H]lestramustine in
meningioma tissue with a dissociation constant of 22-26 nM. Immunohistochemistry revealed an immunoreactivity in
meningioma comparable to that demonstrated in prostatic
carcinoma. The mean concentration (n = 6) of
estramustine-binding protein in
meningioma, as determined by radioimmunoassay was 159 ng/g tissue (range 18-274 ng/g). Moreover, partial characterization using size exclusion chromatography of [3H]
estramustine-labeled
tumor extracts and Western blot analysis of immunoprecipitated samples indicated that the structure of the
estramustine-binding protein in
meningioma is similar to that in rat prostate, with three
polypeptide components of 10, 14, and 16 kDa, as compared to 8, 10-11, and 12 kDa in rat prostate. In conclusion, the novel observation of
estramustine-binding protein and specific binding of
estramustine in
meningioma justify further evaluation regarding the role of
estramustine-binding protein in the growth behavior of
meningioma and the potential for
estramustine and similar
hormone-related drugs in the treatment of relapsing
meningioma.